1. Field of the Invention
The present invention relates to an alternating-current driving-type display device utilizing plasma discharge.
2. Description of the Related Art
Heretofore, there has been known an alternating-current driving-type display device using plasma discharge, i.e. so-called AC (alternating-current)-type plasma display panel (Plasma display panel: PDP). As this AC-type PDP, there are such a plasma display panel which is able to display a light emitted by a discharge gas and such a plasma display panel which is able to excite a fluorescent mnaterial by ultraviolet rays generated by the discharging.
Heretofore, there are known conventional color AC-type PDPs which are driven by two-phase electrodes and by three-phase electrodes.
FIG. 1 shows an arrangement of a color AC-type PDP 1 which is driven by three-phase electrodes. FIG. 1 is a perspective view showing a portion which includes a portion corresponding to one pixel. FIG. 2 is a cross-sectional view taken along the line A--A in FIG. 1 which is parallel to the direction in which address electrodes of FIG. 1 are extended. FIG. 3 is a cross-sectional view taken along the B--B in FIG. 1 which is parallel to the direction in which display electrodes of FIG. 1 are extended.
This color AC-type PDP 1 includes a three-electrode structure in which a pair of display electrodes 2, 2 and an address electrode 3 are opposed to each other in a matrix display unit light-emission region, and in which fluorescent materials 4 (4R, 4G, 4B) are formed on the address electrode 3 side.
That is, a plurality of sets (only one set is illustrated in the figure) of the pair of display electrodes 2, 2 are arrayed on a first substrate, e.g. a front glass substrate 5 on the display surface side. A dielectric layer 6 is formed so as to cover the display electrodes 2, 2. Further, an MgO film having a thickness of several 1000s of angstroms is formed on the surface of the dielectric layer 6 as a protecting layer 7. Reference numeral 8 denotes a bus electrode of a low resistance value formed on the display electrodes 2, 2.
On the other hand, the address electrode 3 for causing the unit light-emission region to become luminous selectively is arrayed on a second substrate opposing the front glass substrate 5, e.g. rear glass substrate 10 in the direction perpendicular to the display electrodes 2, 2, e.g. at a pitch of about 200 microns. Further, a dielectric layer 12 is formed so as to cover the address electrodes 3. A stripe-like partition wall 11 having a width of about 100 microns for determining a spacing size of a discharge space is formed between adjacent address electrodes 3, whereby the discharge space is partitioned at every unit light-emission region in the line direction (extended direction of the display electrodes 2, 2). Also, fluorescent materials 4R, 4G, 4B of three colors of red, green and blue are formed between adjacent partition walls 11 by coating. Incidentally, in the discharge space, there is sealed a Penning gas in which xenon is mixed with neon, for example, as a discharge gas for exciting the fluorescent materials 4 (4R, 4G, 4B) with ultraviolet rays.
Each pixel (picture element) comprising the display screen is composed of three unit light-emission regions of red (R), green (G), blue (B) of the same area arrayed on the line direction.
In this color AC-type PDP 1, after a discharge is started between one display electrode 2 of the selected pair of display electrodes 2, 2 and the selected address electrode 3, the discharge is maintained between the pair of display electrodes 2 and 2 and the fluorescent materials 4 (4R, 4G, 4B) are excited to become luminous by the ultraviolet rays generated by plasma discharge produced at that time. Accordingly, by selectively causing each unit light-emission region to become luminous, it becomes possible to present a full color display by a combination of red (R), green (G), blue (B).
By the way, in such color AC-type PDP 1, in order to make the display pixel become high-definition, it is necessary to reduce a distance between the display electrodes 2 and 2. In this connection, it is necessary to make a distance between the address electrode 3 and the display electrode 2 become equal to the distance between the display electrodes 2 and 2.
However, there is a limit on reducing the distance between the display electrodes 2 and 2. Thus, it is difficult to make the display pixel become high-definition.
If the distance between the electrodes 2 and 2 is less than, for example, 20 microns, then when the fluorescent material having a thickness ranging from 20 to 40 microns is formed, a plasma discharge space 14 shown in FIG. 3 is lost. There is then the risk that a discharge destruction will occur between the electrodes.
Also, even considering the arrangement in which the plasma discharge space 14 is maintained, the portion in which the fluorescent materials should be formed is limited. If the fluorescent materials 4 are reduced, then the brightness becomes low. Further, there is the disadvantage that the fluorescent materials are deteriorated by ion bombardment.